PDF(Pubmed)
Abstract：
The formation of phytoene by condensing two geranylgeranyl diphosphate molecules catalyzed by phytoene synthase (PSY) is the first committed and rate-limiting step in carotenoid biosynthesis, which has been extensively investigated in bacteria, land plants and microalgae. However, this step in macroalgae remains unknown. In the present study, a gene encoding putative phytoene synthase was cloned from the economic red alga Pyropia yezoensis-a species that has long been used in food and pharmaceuticals. The conservative motifs/domains and the tertiary structure predicted using bioinformatic tools suggested that the cloned PyPSY should encode a phytoene synthase; this was empirically confirmed by pigment complementation in E. coli. This phytoene synthase was encoded by a single copy gene, whose expression was presumably regulated by many factors. The phylogenetic relationship of PSYs from different organisms suggested that red algae are probably the progeny of primary endosymbiosis and plastid donors of secondary endosymbiosis.
摘要：
通过由植物烯合酶（PSY）催化的两个香叶基香叶基香叶基二磷酸酯分子缩合形成植物烯是类胡萝卜素生物合成中的第一个承诺和限速步骤，已经在细菌中进行了广泛的研究，陆地植物和微藻。然而,大型藻类的这一步仍然未知。在本研究中,从经济红藻Pyropiayezoensis克隆了一种编码推定的植物烯合酶的基因，该物种长期以来一直用于食品和药品。使用生物信息学工具预测的保守基序/结构域和三级结构表明，克隆的PyPSY应编码八烯合酶；这在经验上通过大肠杆菌中的色素互补得到了证实。这种八烯合成酶由单拷贝基因编码，其表达可能受多种因素调控。来自不同生物的PSY的系统发育关系表明，红藻可能是初级内共生的后代和次级内共生的质体供体。
